The Radiation Therapy Oncology Group (RTOG) is an instrument of cooperative investigations to increase survival, decrease morbidity, preserve function and quality of life, and increase basic understanding of cancer. Its clinical, laboratory, and biostatistical scientists have made progress against major killers of Americans, especially cancer of the esophagus, lung, cervix, prostate, and anal canal. It has demonstrated equivalent outcomes when treatments are comparable for blacks and whites with brain tumors, and carcinomas of the head and neck, lung and esophagus, and similar results for women and men with malignant gliomas, head and neck and lung cancer. The RTOG plans to continue integration of surgical, radiotherapeutic and chemotherapeutic treatments with emphasis on enhancing local-regional tumor control to improve outcomes. It will continue to investigate 3-dimensional conformal radiation therapy and stereotactic radiosurgery, altered fractionation, and chemical and biologic agents. Phase III trials for brain, head and neck, lung, gastrointestinal and genitourinary tumors are active and new hypotheses will be tested within the RTOG or the integroup mechanism when current studies are completed. A comprehensive quality management program monitors protocol compliance, completeness and accuracy of data, institutional audits and timely reporting of results. The RTOG has an entirely independent data safety and monitoring committee, and its protocols are overseen by an institutional review board with expertise in medical ethics. A Translational Research Program (TRP) chaired by a new Vice-Chair for Basic Science is rapidly advancing correlative studies of clinical, cellular and molecular phenomena; the TRP includes pathologists, tumor biologists and physicians representing all disease sites. A new Vice-Chair for Cancer Control oversees interrelated Community Clinical Oncology Program (CCOP), Special Populations, Epidemiology, Late Effects and Quality of Life investigations. The large databases and long-term observations from RTOG studies serve as unique resources to study major types of cancer. A 19% increase in annual accrual of patients for the last three years compared with the prior four years indicates that the studies of the RTOG investigations will be achieved more rapidly and its results will be available to the practice community and to investigators developing future studies.